Unconstrained extrusion?
try pressing Y 2 times again (total of 3 times), until you are free to move the new geometry freely... every time you press Y you set other contraints for the transform. 


after E you are "grabbing" along the face normal.
pressing Y 1st time puts you in "constraint to global Y"
pressing Y 2nd time puts you in "constraint to normal Y"
pressing Y 3rd time puts you in "no constraint at all"


you can see a feedback of these changes in the lower left corner of the 3d window, where coordinates change while you are moving...